Method of fabricating a master model



June 19, 1962 c. A. GENETTI 3,

METHOD OF FABRICATING A MASTER MODEL Original Filed 001;. 5, 1956 2 Sheets-Sheet 1 IN V EN TOR. $94 915.? 4. GI/YEZT June 19, 1962 c. A. GENETTI 3,

METHOD OF F'ABRICATING A MASTER MODEL Original Filed Oct. 5, 1956 2 Sheets-Sheet 2 INVENTOR.

0mm: 4 65V! 7/ United States Patent 3,939,912 METHOD 6F FABRICATIN G A MASTER MGDEL Charles A. Genetti, East Lansing, Mich., assignor to Ken Plastics, incorporated, Lansing, Mich, a corporation of Michigan Original application Oct. 5, 1956, Ser. No. 614,275, now Patent No. 2,918,727, dated Dec. 29, 1959. Divided and this application Nov. 10, 1958, Ser. No. 781,175

11 Claims. (Cl. 156246) The present invention relates to an improved master model or like structure, and to a method of making the same. The present application is a division of my ccpending application, Serial No. 614,275, filed October 5, 1956, now Patent No. 2,918,727.

in accordance with the invention, the model is fabricated throughout of non-metallic material, and is light in Weight, accurate in contour and dimensionally stable. Models of the type contemplated are employed in the automotive industry, for example in making and checking parts, tools and fixtures, and the invention is primarily directed to the production of a master model for use in the automotive industry, though not exclusively limited in this respect.

The method of the invention provides an original model or like structure which adheres strictly to present model duplication procedure, without following resently employed aircraft or wood model procedures.

It Will be apparent as the description proceeds that the method is also well suited to the production of mock-ups, duplications, and like structures.

It is an object of the invention to provide a method of producing a master model which generally follows the shrink-free core principle employed in the construction of models from plastic materials, such as an epoxy resin, and which involves a final splining-in of the plastic ma terial, in reference to contour template elements of plastic material incorporated in the model in an improved fashion. The method avoids the incorporation of metallic template elements permanently and integrally in the model.

Another object is to provide an improved method of manufacturing master models which are very light in weight and inexpensive, and are not subject to parting of the splined-in plastic material from the template elements in reference to which it is splined-in. The invention affords a model which is unique in character, as compared with presently employed aircraft and Wood model constructions.

Yet another object is to provide a high tolerance model structure of great accuracy. To this end the model incorporates a predominmce of pre-cured plastic material, as compared with uncured or unset plastic material employed in binding together the cured components.

Briefly, this involves the application of elongated strips of cured glass laminate across accurately prefabricated template units presenting shot plastic template portions on which the laminate strips are applied in side by side relation to one another. The strips are bonded to the shot plastic edges in accurate conformity therewith, being held against said edges by tubular back-up or reinforce members of cured plastic, which are bonded to the adjacent rear surface of the sheet structure represented by the strips along and in opposed relation to the respective lines of the template units. Upon setting of the bonding material the shot plastic edges are stripped from the remainder of the template units, which leaves a core base structure to which plastic material is applied, being bonded to the base between the shot plastic template elements, as well as to the sides of those elements themselves, in a laterally flush relation to the outer template portions or edges.

The foregoing as well as other objects will be made 3,639,912 Patented June 19, 1962 ice more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a fragmentary perspective view, partially broken away and in section, illustrating in general the procedure of making a portion of a master model in accordance with the method of the invention, as well as being a rear view of said portion of the master model itself;

FIG. 2 is a fragmentary perspective view from the front of said master model portion, showing successive operations in its production;

FIG. 3 is a fragmentary view in enlarged scale in section alon: a line corresponding to line 33 of FIG. 1;

FIG. 4 is a view in enlarged scale and in section along a line corresponding to line 4-4 of FIG. 2, showing the model structure as parted or stripped, along with reference template edges of plastic material, from the remainder of the template structure; and

FIG. 5 is a view in section along line 55 of FIG. 4.

In practicing the invention, a template structure, generally designated 10, is first produced and set up. This structure includes any suitable type of supporting frame, illustrated as a simple base or table 11, to which a series of female template units '12 are rigidly clamped in parallel, laterally spaced relation, as by means of angle iron brackets 13 Each of the template units 12 includes a master female template member 14 of thin, sheet-like metal which is accurately shaped to provide a contoured edge 15 corresponding exactly to the contour of an outer surface element of the model desired to be produced. A parting agent such as wax (not shown) is applied to each of the edges 15 throughout their lengths, following which shot plastic material 1% such as an epoxy resin, thermally or otherwise settable, is applied along the prepared edge 15 and hardened. The plastic material is brought flush with the sides of the plate 14 at the meeting line of edge 15 and the shot plastic 16. Preferably, as illustrated in FIG. 3, the shot plastic is filleted somewhat at 17, its sides converging to the edge 15.

With a group of the template units 12 assembled and rigidly clamped in the desired and accurate spacing, lengths or strips 18 of cured fiber glass laminate are applied across the edges of the shot plastic elements 16,

H which subsequently constitute template elements of the ultimate model structure, and are bonded thereto as by an epoxy type resin adhesive which is cured or set and hardened. The laminate strips 18 may vary in thickness and width but are preferably approximately inch in front to rear thickness. Their width may vary from, say, inch to perhaps several inches, depending upon the contouring of the template unit 12. As so applied they build up to a sheet-like base, generally designated by the reference numeral 19, which develops the contour of g the shot plastic material 16 as the application of the strips proceeds, much in the manner a splining tool does in applying finish material.

Although the width of the strips 18 may vary for the reason mentioned, and also in accordance with the required stilfness of the base 19, their thickness must remain constant, for a reason which will appear. A single thickness layer of the successive, side by side strips 18 is illustrated, however it is within the contemplation of the invention that successive, rearwardly deposited layers may be built up, bonded and set, so long as overall thickness is maintained uniform. It has been found that if any given strip varies considerably in width or thickness along its length it will not maintain a true contour when bent across three or more templates, so that it is difficult to maintain accuracy.

Bonding engagement of the strips 18 with the shot plastic template elements 16 is effected by applying tubular lengths of flexible, spiral cut plastic tube 20 to the rear surface thereof, directly over or in opposed relation to the respective template units 14. The strips are held down by pressure applied to the tube rather than the strips.

The tubes 26 are bonded to the rear of the built up base 19, as by the use of epoxy plastic resin, and following setting, the gear employed to hold the tubes and strips in place is removed. The entire rearwardly exposed area of the model, including strips 18 and tubes 20, is then covered with a layer of fiber glass cloth 21, which is bonded to the area by a plastic adhesive. Suitable supporting and reinforcing frame work, generally designated 22, and preferably in the form of bonded lengths of plastic tubing 23, is then applied to the structure, cementing and setting the same to the shaping tubes 2%, which also constitute part of the supporting and reinforcing structure.

The core or body and bonded template elements are then stripped from the plates 14 of the several template units 12, after which plastic molding compound 24, such as an epoxy resin, is splined in between the forwardly projecting template elements 16, being bonded to the forward surface of the shaped base 19 as well as to the sides of the template elements 16. The application of splined plastic is brought laterally flush with the outer edges of the elements 14 in the usual fashion, and is then cured and hardened to complete the model.

In practice, the thickness of the shot plastic template elements applied to the plates 14 may vary considerably. In the interest of maintaining the amount of uncured plastic compound 24 at a minimum, a thickness of, say, .060 inch is satisfactory. However, the thickness may be increased up to, say /2 inch, although additional uncured compound is of course the result. The fiber glass strips 18 should be applied to the template edge as closely together as possible, and at the proper angle to the template unit 12 to obtain a desired and true contour, which is usually a right angle. The tubular backing members 20 and the supporting frame 22 constituted by the tubing 23 must be substantial enough to sustain stresses which may arise in the core or base 19 in the bending of the plastic strips 18. These strips, in turn, must be substantial enough to hold the finish, spliced-in material 24 and the template elements 16 accurately to the original set up contours of the female template edges 15'. This prevents warping or shrinking of the core such as would necessitate reshooting the templates with plastic.

The invention affords a method of making master models and the like, in which a core of cured, shrink-free material having the spring-like qualities of a glass laminate is employed to obtain accuracy of contour, and in which the splined-in and job-cured plastic, being relatively thin, is held dimensionally accurate by the shrinkfree core. The product is very light in weight, inexpensive, dimensionally stable, shrink and crack-free, and many duplications thereof may be made from asingle set-up of the master female template members 14.

What I claim as my invention is:

1. A method of fabricating a master model or like structure, comprising forming a template presenting a shaped outer edge longitudinally conformed with a sectional outer surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied therealong in spaced zones, bonding a sheetlike base across said layer in general conformity at said template element with said template edge but in inwardly spaced relation thereto, separating said base and layer from said template, and, with the base and layer exposed, molding settable plastic material in the space between said zones to said base and layer in laterally flush relation to the outer edge of the latter.

2. A method of fabricating a master model or like structure, comprising forming a template presenting a shaped outer edge longitudinally conformed with a sectional outer surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied the-realong in spaced zones, bonding elongated fiber glass strips in side to side relation transversely across said layer to provide a sheet-like base in general conformity at said template element with said template edge but in inwardly spaced relation thereto, separating said base and layer from said template, and, with the base and layer exposed, molding settable plastic material in the space between said zones to said base and layer in laterally flush relation to the outer edge of the latter.

3. A method of fabricating a master model or like structure, comprising forming a template presenting a shaped outer edge longitudinally conformed with a sectonal outer surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied therealong in spaced zones, bonding elongated fiber glass strips in said to side relation transversely across said layer to provide a sheet-like base in general conformity at said template element with said template edge but in inwardly spaced relation thereto, reinforcing said base on the side thereof opposite said layer, separating said base and layer from said template, and, with the base and layer exposed, molding settable plastic material in the space between said zones to said base and layer in laterally flush relation to the outer edge of the latter.

4. A method of fabricating a master model or like structure, comprising forming a template presenting a shaped outer edge longitudinally conformed with a sectional outer surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied therealong in spaced zones, bonding elongated fiber glass strips in side to side relation transversely across said layer to provide a sheet-like base in general conformity at said template element with said template edge but in inwardly spaced relation thereto, re inforcing said base on the side thereof opposite said layer by bonding elongated brace members thereto along the lines of said template edge, separating said base and layer from said template, and, with the base and layer exposed, molding settable plastic material in the space between said zones to said base and layer in laterally flush relation to the outer edge of the latter.

5. A method of fabricating a master model or like structure, comprising forming a template unit including a plurality of laterally spaced plate-like template elements each presenting an outer edge longitudinally conformed with an outer sectional surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied therealong, bonding a sheet-like fiber glass base to said layers in general conformity at said template elements with said templat edges but inwardly spaced therefrom, separating said base and layers from said templates, and with the base layers exposed, molding settable plastic material to said base and to and between said layers in laterally fins-h relation to the outer edges of the latter.

6. A method of fabricating a master model or like structure, comprising forming a template unit including a plurality of laterally spaced plate-like template elements each presenting an outer edge longitudinally conformed with an outer sectional surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied tlrerealong, bonding elongated fiber glass strips in side to side relation transversely across said layers to provide a sheet-like fiber glass base in general conformity at said template elements with said template edges but inwardly spaced therefrom, separating said base and layers from said templates, and, with the base and layers exposed, molding settable plastic material to said base and to and between said layers in laterally flush relation to the outer edges of the latter.

7. A method of fabricating a master model or like structure, comprising forming a template unit including a plurality of laterally spaced plate-like template elements each presenting an outer edge longitudinally conformed with an outer sectional surface element of the structure to be fabricated and having a thin layer of set plastic material separably applied therealong, bonding elongated fiber glass strips in side to side relation transversely across said layers to provide a sheet-like fiber glass base in general conformity at said template elements with said template edges but inwardly spaced therefrom, reinforcing said base by bonding elongated brace members thereto along the lines of said template edges, separating said base and layers from said templates, and, with the base and layers exposed, molding settable plastic material to said base and to and between said layers in laterally flush relation to the outer edges of the latter.

8. A method of fabricating a master model or like structure, comprising forming a template unit which is longitudinally conformed with a sectional outer surface elemental contour of the structure to be fabricated, applying a settable plastic material to said template unit in separable engagement with the latter along surfaces spaced from one another transversely of the direction of longitudinal conformity of said template unit, thereby to provide spaced projecting shaped template surfaces for said structure which are separable from said template unit, bonding a sheet-like base across said template surfaces and in general conformity therewith, but in inwardly spaced relation to said template unit, separating said base and template surfaces from said template unit, and molding settable plastic material to said base and template surfaces, as separated from said template unit, in the space between and in laterally flush relation to the outer faces of the template surfaces.

9. A method of fabricating a master model or like structure, comprising forming a template unit which is longitudinally conformed with a sectional outer surface elemental contour of the structure to be fabricated, applying a settable plastic material to said template unit in separable engagement with the latter along surfaces spaced from one another transversely of the direction of longitudinal conformity of said template unit, thereby to provide spaced projecting shaped template surfaces for said structure which are separable from said template unit, bonding a sheet-like base across said template surfaces and in general conformity therewith, but in inwardly spaced relation to said template unit, reinforcing said base by the application of shaped reinforcing elements along the Zones of its longitudinal conformity with said base, separating said base and template surfaces from said template unit, and molding settable plastic material to said base and template surfaces, as separated from said template unit, in the space between and in laterally flush relation to the outer faces of the template surfaces.

10. A method of fabricating a master model or like structure, comprising forming a template unit which is longitudinally conformed with a sectional outer surface elemental contour of the structure to be fabricated, applying a settable plastic material to said template unit in separable engagement with the latter along surfaces spaced from one another transversely of the direction of longitudinal conformity of said template unit, thereby to provide spaced projecting shaped template surfaces for said structure which are separable from said template unit, bond ng a sheet-like base composed of elongated, pre-set fiber glass strips in side by side engagement with one another across said template surfaces and in general conformity as to longitudinal contour with the latter, but in inwardly spaced relation to said template, separating said base and template surfaces from said template unit, and molding settable plastic material to said base and template surfaces, as separated from said template unit, in the space between and in laterally fiush relation to the outer faces of the template surfaces.

11. A method of fabricating a master model or like structure, comprising forming a template unit which is longitudinally conformed with a sectional outer surface elemental contour of the structure to be fabricated, applying a settable plastic material to said template unit in separable engagement with the latter along surfaces spaced from one another transversely of the direction of longitudinal conformity of said template unit, thereby to provide spaced projecting shaped template surfaces for said structure which are separable from said template unit, bonding a sheet-like base composed of elongated, pre-se't fiber glass strips in side by side engagement with one another across said template surfaces and in general conformity as to longitudinal contour with the latter, but in inwardly spaced relation to said template, reinforcing said base by the application of shaped reinforcing elements along the zones of its longitudinal conformity with said base, separating said base and template surfaces as thus reinforced, from said template unit, and molding settable plastic material to said base and template surfaces, as separated from said template unit, in the space between and in laterally flush relation to the outer faces of the template surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 2,715,596 Hawley Aug. 16, 1955 2,777,790 Kish Jan. 15, 1957 2,845,379 Bey July 29, 1958 

1. A METHOD OF FABRICATING A MASTER MODEL OR LIKE STRUCTURE, COMPRISING FORMING A TEMPLATE PRESENTING A SHAPED OUTER EDGE LONGITUDINALLY CONFORMED WITH A SECTIONAL OUTER SURFACE ELEMENT OF THE STRUCTUR TO BE FABRICATED AND HAVING A THIN LAYER OF SET PLASTIC MATERIAL SEPARABLY APPLIED THEREALONG IN SPACED ZONES, BONDING A SHEETLIKE BASE ACROSS SAID LAYER IN GERNERAL CONFORMITY OF SAID TEMPLATE ELEMENT WITH SAID TEMPLATE EDGE BUT IN INWARDLY 